New Space Engine Could Turn Tiny CubeSats into Interplanetary Explorers

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Researchers plan to launch a tiny spacecraft to Earth orbit and
beyond within the next 18 months, in a key test of new propulsion
technology that could help cut the cost of planetary exploration
by a factor of 1,000.

The scientists and engineers are developing a new plasma
propulsion system designed for ultrasmall CubeSats. If all goes
well, they say, it may be possible to launch a life-detection
mission to Jupiter's ocean-harboring moon Europa or
other intriguing worlds for as little as $1 million in the
not-too-distant future.

"We want to enable new missions that right now cost about $1
billion, or maybe $500 million — to go, for example, explore the
moons of Jupiter and Saturn," said project leader Ben Longmier, a
plasma physicist and assistant professor at the University of
Michigan. [ 6
Promising Places for Alien Life in the Solar System ]

To get the ball rolling, Longmier and his team
launched a crowdfunding campaign on the website
Kickstarter Thursday (July 4). They hope to raise a minimum of
$200,000 by Aug. 5, which should be enough to loft the miniature
thruster on its maiden space voyage.

Miniature thruster technology

CubeSats are cheap and tiny spacecraft that weigh just
11 pounds (5 kilograms) or so. At present, they're generally
restricted to Earth orbit, where they circle passively until
their orbits decay and they die a fiery death in the planet's
atmosphere.

But the new propulsion system — which the team calls the CubeSat
Ambipolar Thruster, or CAT — could change all that, turning such
bantam spacecraft into interplanetary probes, Longmier and his
colleagues say.

CAT is a plasma engine, generating thrust by accelerating
superheated ionized gas out of a discharge chamber. The CAT
thruster is powered by solar panels, and permanent magnets will
guide the plasma out the back of the spacecraft.

CAT is similar in concept to the ion engine that powers NASA's
Dawn spacecraft, which orbited the protoplanet Vesta for more
than a year and is now on its way to study Ceres, the largest
body in the main asteroid belt between Mars and Jupiter. Over
long periods of time, such thrusters can accelerate spacecraft to
higher speeds than typical chemical rockets can achieve.

But with CAT, everything must work on the micro scale. The
thruster and power systems will weigh less than 1 pound (0.5 kg),
while the supply of propellant — likely either iodine or water,
though many different substances could be used — will be capped
at about 5.5 pounds (2.5 kg), researchers said. [ Gallery:
The Solar System's Deep-Space Probes ]

Most of the CAT components have been built and tested
individually, and the team is making good progress toward
incorporating them into a unified whole, researchers said.

"The hurdles that exist right now are getting our newly designed
thruster up and running. We think we're about three weeks from
that," Longmier told SPACE.com. "We're really sort of ramping up
and hitting full tilt right now."

To Earth orbit and beyond

The main goal of the new CAT Kickstarter campaign is to raise
enough money to space-test the engine in Earth orbit. The team is
planning to launch its first probe within the next 18 months,
though it may be possible to get off the ground even sooner,
Longmier said.

The team plans to send the maiden CAT-equipped probe out into
deep space as well — not all the way to Europa or Saturn's
geyser-spewing moon
Enceladus, but far enough to demonstrate CAT's capabilities.

"Our secondary goal is getting it out of Earth orbit and proving
to the community that this thing works," Longmier said. "If it
does work, it's a lot easier to get funding and write grants in
the traditional sense."

Raising $200,000 should make all of this possible, while meeting
other funding milestones will allow the CAT team to tackle
"stretch goals." If the Kickstarter campaign nets $500,000, for
example, the team will fast-track its space trip by purchasing a
commercial launch, while raising $900,000 will enable a
two-CubeSat "space race" to escape Earth orbit.

Longmier and his core team at the University of Michigan are
working with experts at a variety of institutions, including
three different NASA centers — Ames Research Center in Moffett
Field, Calif., the Jet Propulsion Laboratory in Pasadena, Calif.,
and Glenn Research Center in Cleveland, Ohio.

The asteroid-mining firm
Planetary Resources is another partner. The
billionaire-backed company, which counts Google execs Larry Page
and Eric Schmidt among its investors, is interested in possibly
using CAT-equipped probes to do up-close asteroid reconnaissance
on the cheap, Longmier said.

"That's sort of where we come in — sending that small spacecraft
out as a scout, a radio beacon, to go radiotag it," he said.

Asteroid tagging is just one of many potential applications for
the technology, CAT team members say. A fleet of CAT-powered
CubeSats could also provide cheap global Internet access, for
instance, or study the impacts of solar eruptions on Earth's
neighborhood, helping scientists better understand and predict
space weather.

And then there's the lure of mounting stripped-down, $1 million
life-detection missions to Europa, Enceladus or other intriguing
and farflung worlds. Such efforts may be possible soon, thanks to
CAT, the increasing efficiency of solar panels, the decreasing
size of microprocessors and other technological advances,
Longmier said.

"I think we have the opportunity — for the first time, more or
less, in history — to go and see if we can make these detections
of life within our own solar system," Longmier said. "Not just
looking at them, but going and taking sensors, doing in situ
measurements, flying through the
plumes of Enceladus with small spacecraft. We think we
can do that in the relatively near future."